Characteristics of Pediatric IgA Nephropathy with Gross Hematuria after Vaccination with a SARS-CoV-2 Vaccine

There have been a substantial number of gross hematuria cases reported after a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in adults, and many of these patients have immunoglobulin A nephropathy (IgAN) as their primary disease. Since pediatric cases remain few, we analyzed the clinical characteristics of 14 pediatric IgAN cases presenting with gross hematuria following SARS-CoV-2 vaccination. This cohort comprised 3 cases from our hospitals and 11 cases under the age of 18 retrieved from a PubMed search. We also compared the clinical characteristics of the 14 pediatric cases with previously reported adult cases with gross hematuria after SARS-CoV-2 vaccinations. Most children (12/14) developed gross hematuria the day after the second dose. Among the 7 cases with microscopic hematuria at the vaccination, three patients developed kidney dysfunction. Conversely, no patient (0/3) who was in urinary remission at the time of vaccination developed kidney dysfunction. Similarly, among 9 patients who had not diagnosed with IgAN at the vaccination, five developed kidney dysfunctions, while among 4 patients who had diagnosed IgAN and was under/post treatment, only 1 patient developed kidney dysfunction. A higher rate of kidney dysfunction was observed in pediatric cases than in adult cases (42.9% vs. 0%, 28.6%). IgAN cases in children with gross hematuria after SARS-CoV-2 vaccinations had different clinical characteristics compared to adult cases.